DNA-synthesizing complexes are present within human and bovine sperm nuclei and in cell-free seminal fluid. The associated DNA polymerase will be purified, characterized and used for the production of specific antisera in order to determine its relationship to other DNA-synthesizing enzymes and to assess its functional significance during spermatogenesis or embryogenesis. A (3H)DNA product will be prepared from the complex fur use as a probe to detect complementary sequences in the DNA and RNA from a variety of tissues.